Onstage, above the smoky darkness of the dance floor, Who bassist John Entwistle is plugging in his amp. Beside him, Guns n' Roses guitarist Slash shakes his long black mane and gets ready to play. They issue a call for a "real blues guitarist," and a squat figure topped by a tilted beret steps forward. Unintimidated by the two rock biggies, raunchy comedian Sam Kinison straps on his guitar. With a devilish cackle, he looks out toward his pal Julian Lennon and shrieks, "I want to dedicate this song to a [expletive] who won't get onstage, and he knows who he is!"

No, this bizarre scene is not the product of some desperate record producer's fevered imagination—it's just another Monday night free-for-all at Hollywood's hot spot of the moment, China Club. With musical superstars such as Elton John and Rick James spontaneously hopping onstage, while Madonna, Warren Beatty, John Goodman and George Harrison watch from the floor, China Club is not just hot it's on the edge of meltdown. "I've never seen anything like it" says Kinison. "It stepped in and took over L.A."

When China Club first opened its doors last August the L.A. club scene was about as stable as the San Andreas Fault Hangouts like Vertigo, Rubber and Stock Exchange were flashing hot and cold with the speed of a paparazzo's strobe. Nevertheless, business partners Michael Barrett Danny Fried and David Boyd, who had invigorated New York City's nightlife with their original China Club in 1985, decided to test their after-hours magic out West To the tune of $2 million, they spent two years refurbishing a former restaurant with a stage and dance floor, state-of-the-art sound system, chic dining room and enough secret byways and dimly lit nooks to hide incognito celebs. "The idea was not to be a trendy disco," says Fried, a former clothing merchant "We wanted a place where people in the music industry would feel at home."

That happened almost instantly. Although the club is open seven nights, Monday and Thursday quickly evolved into star-studded jam sessions featuring musicians like Teena Marie, soul singer Michael Bolton and former Eagle Joe Walsh, in undreamed-of combinations. The Who's Entwistle first stopped by one night in November and returned twice weekly thereafter. "I had so much fun," he says, "I spent $8,000 on a new bass rig to use here." Occasionally, amateurs in the audience—like Kinison—also join in the fun. Even tennis bad boy John McEnroe once strutted his stuff on guitar.

China Club was confirmed as the epicenter of ultrahip in November, when an impromptu jam by Entwistle, Bolton and Steve Van Zandt was followed by an unexpected 40-minute concert by Elton John, who tore through such classics as "I Heard It Through the Grapevine" and "Twist and Shout," as well as his own standards. "That was an incredible night," recalls the club's maitre d', Natalie Singer. "It was the only time I can recall everyone in the entire club stopping to watch and listen. Not a single person moved."

Of course, for any club to be truly hot, the action offstage must also sizzle. Besides Madonna and Warren, those paying the $10 cover charge have included Justine Bateman, Danny Aiello, Katie Wagner, Sally Kellerman, even Ed McMahon. Julian Lennon has his own regular ringside table. "You meet other actors and musicians who you might never meet anywhere else," says Lennon, who adds that he recently had a lengthy conversation with Robert De Niro at the club.

Tonight is fairly typical. Songwriter Stephen ("It Might Be You") Bishop is resting against the bar. The Milli Vanilli duo are cruising the tables where their fellow rockers are hanging out. Julian Lennon is swaying with a lean blond in a slow dance near the stage. Joni Mitchell has wandered into the house band's warm-up room, sparking rumors that she might perform a song, but it turns out she's only looking for a phone. Owner Fried helps her find one, then returns to the room smiling. "Joni isn't going to play tonight," he informs a handful of hopeful fans. "But she says that she'll come back another night." Chances are, everyone else will too.

—Jeannie Park, Todd Gold in Los Angeles